Variable condenser



Nov. 20, 1928. 1,692,607

- w. AULL, JR

VARIABLE CONDENSER Filed Sept. 1926 4 Sheets-Sheet l wan Nov. 20, 1928. 1,692,607

w. AULL, JR

VARIABLE CONDENSER Filed Sept. 1, 1926 4 Sheets-Sheet 2 Nov. 20, 1928.

W. AULL, JR

VARIABLE CONDENSER Filed S pt. 1926 4 Sheets-Sheet Nov. 20, 1928.

w. AULL, JR

VARIABLE CONDENSER ,Fi 1926 4 Sheets-Sheet 4 INVENTOR 77118012 A1111, Jr. BY

Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

WILSON .AULL, JR., OF ASTORIA, NEW YORK.

VARIABLE CONDENSER.

Application filed September 1, 1926. Serial No 132,974.

The ordinary form of'variable condenser, used almost universally in radio reception, consists of two sets of fiat plates, one set fixed in position and the other set secured to a rotatable shaft and arranged to mesh or interleave with the stationary plates.

The chief disadvantage inherent in this type of condenser is that slight mechanical variations in the shaft or bearings arev amplified by lever action so that one-thousandth of an inch play in the hearing may well become several thousandths at the edges of the rotor plates with consequent variation 111 capacity of the condenser for a given angular setting. Likewise, the outer edges of the movable plates are not supported and warping of the plates gives a similar result.

The chief improvement in my invention relates to the use of what I have termed a rim bearing,-a bearing which may, though not necessarily, extend around the periphery rather than through the center of the condenser. A slight mechanical inaccuracy in the hearing would, with this form of construction, not be amplified but minimized if the bearing had a greater radius than that of the movable plates. Moreover, the movable section is much more rigidly supported by this mode of construction.

There are many other advantages inherent in such an arrangement. One of these is that much less clearance distance may be safely used between rotor and stator plates. That is, instead of an air gap of thirty or forty thousandths of an inch between plates as is usual, less thanone-half this distance can be used with greater safety and uniformity of capacities for given settings than is now obtainable, assuming that the design is skillfully carried out. Thus, fewer plates are necessary for a. given capacity with consequent saving in bulk, material and labor;

Due to the short distance between plates, stray electro-static fields in the condenser are reduced to a minimum and a very small total volume of dielectric is used with consequent gain in the direction of low dielectric losses. Likewise, by the use of die castings, a one-piece rotor and a one-piece stator may be used with a better power factor resulting, as compared to a multi-plate arran ement.

Fig. 1 is a transverse sectionaview of one form of condenser embodying improvements of In invention, the section being taken on the p ane of the line 11 of Fig. 2.

Fig. 2 is a rear view of the same form of device, one of the stator plates being removed and shown separately in Fig. 3.

Fig. 4 is a horizontal sectional view of another form of construction, the parts of which are particularly intended to be made of sheet metal.

Fig. 5 is a front view of the principal parts of the device of Fig. 4.

Fig. 6 is a rear view of the rotor of Fig. 4.

Fig. 7 is a transverse sectional view of another modification.

Fig. 8 is a rear view of the same.

Fig. 9 is a front view of the same, omitting the panel and adjusting knob.

Fig. 10 is a horizontal sectional view of another form of construction, showing a multiple-plate type.

Fig. 11 is a rear view of the same.

Fig. 12 is a sectional view of the rotor of Fig. 10.

Figs. 13, 14, and 15 are fragmentary sections, showing various ways in which the rims of the rotor may be separated.

I In the form shown on Sheet 1, the bed plate 16 is adapted to be secured to any suitable support, as, for instance, a panel 17, in any suitable manner. The relatively stationary member which is usually called a stator, is separated in this form by a rim 18. This rim is secured to the bed plate in any suitable manner, as, for instance, by means of a plurality of screws 19 with spacers 20. The stator plates 21 are insulated from the rim 18 and may be insulated from each other, or electrically connected together, depending upon whether they are to be used as separate capacity elements or as a common element in a multiple-plate condenser. In the form shown, each plate is connected to the rim by two insulating pieces 22 and in order to reduce the dielectric losses, I prefento provide lugs 23 and 24 which project from the plane of the rim and plates. The insulating strips may be secured by rivets or screws such as 25. The lugs may be cast integral with the rim and stator, or may be resilient so as to permit compression and consequent variation in the planes of the various stator sections for the purpose of equalizing the capacities of the condenser sections. In this form the three stator plates 21 are connected by a spider 26 formed of insulating material. This spider in turn is connected by a screw 27 to the spacer 28 which in turn is secured by a screw 29 to the bed plate 16.

The rotor consists of a rim 30 with in washer 34 are interposed between the front of the rotor and the back of the bed plate 16 so as to press the rotor yieldingly against its seat in the flange 32. The plate 35 has a plurality of pins 36 which extend through the bed plate 16 and engage the washer 34. The screw 37 which extends through the plate 35 and the spider 26 serves to draw the parts together so that more or less pressure can be brought to bear on the spring 33 through the washer 34 to increase the thrust of the rotor rim 30 against the flange 32.

It will be seen that the rotor is supported entirely at its periphery rather than at the center, which latter is the customary method. The rotor may be turned in any suitable manmer, for instance, by a knob 38 and pinion 39, meshing with a gear or gear segment 40. The rotor is symmetrical with respect to gravity which is important in a condenser of this type when ball bearings are utilized. A multiple condenser of this type has less bearing surface for a given total capacity area than a plurality of rim bearing condensers mechanically connected to operate in tandem inasmuch as the bearing surface increases directly as the diameter, whereas the capacity area increases about as the square of the plate diameter. In the form shown, the condenser provides three separate sections in sets not materially greater than would ordinarily be occupied by a single unit condenser.

In the form shown on Sheet 2, bed plate 41 carries an annular ring 42 on which the rotor 43 is mounted. A sleeve 44 passes through the bed plate and throu h the rotor and is secured in place by mem ers 45 and 46 and set screws 47 and 48. The rear end of the sleeve 44 may be split so that it may be compressed by the set screw 47 against the shaft 49. Adjusting knob 50 may be mounted on the outer end of the shaft 49 for turning the rotor in the usual way. The shaft, however, has no bearing in the bed plate 41 or the panel 51, but is merely there to turn the rotor.

The stator plate 52 is supported by insulating strips 53 which in turn are secured to the ring 42 which forms the outer bearing for the rotor. The spring 54 may be interposed between the member 46 and the bed plate 41 to resiliently hold the rotor against the bearing ring 42. Any number of condenser units may be supported with their rotors on the shaft 49 and their bed plates secured to the side bars 55.

In the form shown, in Sheet 3, the member 60 is adapted to be suitably secured to a support such as a panel 61. The rotor 62 has its perlphery supported on the bearing flange 63 in the member 60. The rotor shaft 64 may elx'tend through the panel 61 and be provided with any suitable form of knob and dial 65. To strengthen and balance the rotor. it preferably has a rim 66 which extends all around it for engagement with the flange 63. Reinforcing ribs or spokes 67 are also preferably provided. The bearing member in this form is provided with a web 68 which extends inwardly to support the spring 69 which serves to press against a nut 70 on the screw 71 so as to press the rotor against its peripheral bearing.

The stator plate 72 is sup orted from the bearing member 60 by insn ating strips 73. The bearing member 60 and the stator plate is preferably provided with bosses or lugs 74 and 75, respectively, so as to space the connecting strip 73 away from the plane of the stator and avoid dielectric losses.

In the form shown in Figs. 10, 11, and 12, bed plate supports the bearing ring 81.

I The stator member 82 is also supported by the bed plate by insulators 83. The stator may be provided with any number of leaves or plates, such as 84 and 85. The rotor member 86 has a flange 87 supported in the bearing ring 81 and held in place by spring ring 88. The rotor is provided With plates such as 89, 90, and 91. In this case the rotor is provided with an internal gear 92 in which the pinion 93 on the shaft 94 of the knob 95 meshes.

In the form shown in Fig. 13, the rim of the rotor 96 is supported in a bearing ring 97. The pressure may be adjusted by the spring ring 98 and screws 99. The stator 100 is supported by insulating strips 101 which extend inwardly from the bearin ring 97. Spring washers 102 may be provided so as to permit a stator to be adjusted to and from the rotor by means of screws 103 which compress or release the spring 102.

In the form shown in Fig. 14, the'bearing rings and stator and rotor plates are intended to be stamped from sheet metal so that the parts stamped out of the bearing rings 105 and 106 may constitute the stator and be understood, however, that the rotors may be supported by ball bearings arranged at their peripheries as shown in Fig. 15. In this particular form used for the purpose of illustration, the bed plate 115 supports a bearing ring 116' which in turn supports the stator 117. The rotor 118 and the bearing ring 116 are provided with suitable grooves, constituting raceways for the balls 119.

In all of the forms shown and described, it

will be seen that the rotating member is supported not on a central shaft as has been customary in this art, but in an annular hearing at its periphery, removed quite a distance from the axis. The result is that the rotor is not only protected against injury, displacement, or warping by any cause, but the rotor can be designed to be spaced away from the stator at'a minimum distance with assurance that this spacing can always be secured and maintained in manufacture, assembly, and

use.

This arrangement also peculiarly lends itself to shielding against outside disturbances by reason of its compactness and the method of rim support.

It is also possible by reason of the close spacing of the plates to obtain a desired capacity with fewer plates than are required by the usual methods of construction.

It will be understood that various features of the different forms of construction may be combined in other constructions, for instance, the multiple support type of Figs. 1, 2, and 3 may be further developed by making the rotor and stator plates of multiple thickness, as shown in Fig. 10

It will also be understood that the plates may be of uniform thickness or wedge-shaped or tapered as is commonly employed in various types of condensers. It will also be obvious that the effect of tapered or Wedgeshaped plates may be produced by having the plane of the bearing support for the rotor inclined somewhat with respect to the plane of the stator plate or plates, or the stator plates might themselves be either wedgesha ed. or somewhat inclined with respect to t e plane of the rotor surface.

I claim:

1. A condenser comprising an outer hearing ring, a substantially rigid rotor plate having its outer edge supported by said bearing ring and its center free and a stator plate supported from said outer bearing ring but insulated therefrom. 1 g

2. A condenser comprisin an outer ring having a substantially contlnuous annular bearing surface, a rotor plate havingit souter edge supported on said bearing surface and adjustable means for yieldingly pressing the outer edge of said rotor plate against said bearing surface.

3. A condenser having an outer metal bearing ring, a rotor having its outer edge supported thereby, a stator, a number of insulating strips secured to and spaced apart from each other' circumferentially of the bearing ring andhaving their inner ends secured to said stator, a hubsupported by said stator and means carried by said hub for tatably supported within the bearing ring,

and a plurality of stator sections supported within said ring and insulatedfrom each other and from said ring.

6. A multiple circuit condenser comprising a face plate, an outer ring secured thereto and having a substantially continuous bearing surface, a rotor plate having its outer edge rotatably supported on said bearing surface, said rotor plate having a plurality of openings with active sections between them, a spring device located between said face plate and said rotor plate and pressing said rotorplate against said.bearing ring and a number of circumferentially spaced stator plates mounted within said ring with one face of each adjacent said rotor plate.

7 A condenser having an outer ring having an annular bearing surface, a rotor plate having its outer edge supported solely by said ring, a stator plate supported adjacent said rotor plate, said rotor plate having gear teeth and a drive pinion eccentric of said rotor plate and meshing with said gear teeth for rotating said rotor plate with respect to said stator plate.

' WILSON AULL, JR. 

